Sensitivity of Colletotrichum lindemuthianum from green beans to fungicides and race determination of isolates from State of São Paulo, Brazil

This study determined the physiological races of Colletotrichum lindemuthianum isolates, causal agent of anthracnose, collected in green bean producing regions, and assessed the in vitro and in vivo sensitivity of isolates to fungicides. Physiological races of isolates were determined by inoculation of bean differential cultivars under controlled conditions. In vitro sensitivity of colony growth and conidial germination were evaluated for carbendazim, chlorothalonil, copper oxide, mancozeb, pyraclostrobin, thiophanate-methyl and for the mixtures of mancozeb + copper oxychloride, metiram + pyraclostrobin and thiophanate-methyl + chlorothalonil at concentrations of 1, 10, 100 and 1000 μg/mL on PDA medium. In vivo sensitivity was determined in detached primary leaves of green beans previously treated with the same fungicides (commercial doses) recommended for the crop, and then inoculated with conidial suspensions of C. lindemuthianum. C. lindemuthianum isolates were identified as belonging to races 65 and 81. Treatments with pyraclostrobin and the mixture metiram + pyraclostrobin were the most effective in inhibiting the colony growth and conidial germination in vitro, a result also observed for the in vivo experiments, where these chemicals were the most effective in controlling the green bean anthracnose.